Effects of Different Laying Hen Species on Odour Emissions

Abstract

Odour is one of the main environmental concerns in the laying hen industry and may also influence animal health and production performance. Previous studies showed that odours from the laying hen body are primarily produced from the microbial fermentation (breakdown) of organic materials in the caecum, and different laying hen species may have different odour production potentials. This study was conducted to evaluate the emissions of two primary odorous gases, ammonia (NH3) and hydrogen sulphide (H2S), from six different laying hen species (Hyline, Lohmann, Nongda, Jingfen, Xinghua and Zhusi). An in vitro fermentation technique was adopted in this study, which has been reported to be an appropriate method for simulating gas production from the microbial fermentation of organic materials in the caecum. The results of this study show that Jingfen produced the greatest volume of gas after 12 h of fermentation (p 3 emissions (p 2S emissions of Zhusi and Hyline were higher than those of Lohmann, Jingfen and Xinghua (p 2S emissions (p 3 + H2S (39.94 µg). The results for the biochemical indicators showed that the concentration of volatile fatty acids (VFAs) from Zhusi was higher than that for the other five species, while the pH in Zhusi was lower (p 4+), uric acid and urea in Xinghua were lower than those in the other species (p 42− concentration during the fermentation processes (p 3 emission is positively related to urease activities but is not significantly related to the ureC gene number. Furthermore, H2S emission was observed to be significantly related to the reduction of SO42− but showed no connection with the aprA gene number. Overall, our findings provide a reference for future feeding programmes attempting to reduce odour pollution in the laying hen industry.

Keywords

• ammonia
• hydrogen sulphide
• laying hen
• species
• in vitro fermentation